Fluoropolymers, methods for their production, and thermosetting compositions containing them

ABSTRACT

Fluoropolymers are disclosed. The fluoropolymers include (i) units derived from a fluoromonomer having the formula F 2 C═CXY, where X is CF 3  and Y is either F or CF 3 , and (ii) units derived from at least one donor monomer. In the disclosed fluoropolymers, units (i) and (ii) are distributed along the fluoropolymer chain in a substantially alternating fashion. Also disclosed are thermosetting compositions containing such fluoropolymers, substrates coated with such compositions, methods for making such compositions, and methods for coating substrates with such compositions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 60/614,699, filed Sep. 30, 2004, which isincorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to polymers formed from fluorinecontaining monomers. The present invention is also directed to theinclusion of such polymers in coating compositions, such asthermosetting coating compositions. The present invention is alsodirected to methods for making and using such compositions, multi-layercomposite coatings that include a coating layer deposited from such acomposition, and substrates at least partially coated with suchcompositions.

BACKGROUND OF THE INVENTION

Hydroxy-functional fluoropolymers are known to be useful in coatingcompositions. For example, U.S. Pat. No. 4,345,057 details the synthesisof fluorinated ethylene-hydroxy-alkyl vinyl ether (FEVE) copolymers andtheir application in thermosetting coating compositions. Such coatingsare useful in forming high gloss, durable topcoats for building panels,automotive body panels, and automotive body parts, among other things.

Notwithstanding their excellent properties, the use ofhydroxyl-functional vinyl ethers as the source of the reactable hydroxylgroup in these fluoropolymers provides a coating polymer that isrelatively expensive. While the good durability of these FEVE coatingsis known in the coatings industry, there is a need for morecost-effective fluoropolymers that can provide coatings having similarproperties.

U.S. Pat. No. 6,153,697 discloses durable, chemically-resistant filmsmade from terpolymers derived from fluoromonomers, olefins, and diestersof unsaturated anhydrides wherein at least one of the esterifying groupsincludes a hydroxyl group. While coatings containing such terpolymersmay provide cost-efficient compositions that have many of the highlydesirable properties of those derived from hydroxyl-functionalfluoropolymers, such as those mentioned earlier, these compositions havethe disadvantage of requiring the use of a diester of an unsaturatedanhydride, which is a specialty monomer that is not necessarily readilyavailable.

Thus, there is a need for fluoropolymers derived from readily availablemonomers, which are useful in providing thermosetting coatingcompositions that can result in cost-effective coatings havingdurability properties similar to those that include FEVE copolymers.

SUMMARY OF THE INVENTION

In one respect, the present invention is directed to coatingcompositions, such as thermosetting coating compositions. Thesethermosetting compositions comprise a fluoropolymer composition and acrosslinking agent. In these embodiments, the fluoropolymer compositionscomprise a reactive functional group containing fluoropolymer comprising(i) units derived from at least one fluoromonomer of the formulaF₂C═CXY, where X is CF₃ and Y is either F or CF₃ and (ii) units derivedfrom at least one donor monomer, such as a mild donor monomer. In thesefluoropolymers, the units (i) and (ii) are distributed along thefluoropolymer chain in a substantially alternating fashion. Thecrosslinking agent comprises at least two functional groups reactivewith the functional groups of the fluoropolymer.

The present invention is also directed to multi-layer composite coatingswherein at least one coating layer is deposited from a composition thatcomprises a thermosetting composition of the present invention. Inaddition, the present invention is directed to substrates at leastpartially coated with such a thermosetting composition, or suchmulti-layer composite coatings.

In another respect, the present invention is directed to a fluoropolymercomposition that comprises (i) units derived from at least onefluoromonomer of the formula F₂C═CXY, where X is CF₃ and Y is either For CF₃, and (ii) units derived from at least one donor monomer, such asa mild donor monomer. In these fluoropolymers, at least 90% of the units(i) and (ii) are distributed along the fluoropolymer chain in analternating fashion. Moreover, these fluoropolymers have a numberaverage molecular weight ranging from 500 to 10,000. In certainembodiments, these fluoropolymers comprise reactive functional groups.

In still another respect, the present invention is directed to methodsof making a fluoropolymer composition. These methods of the presentinvention comprise (a) providing a donor monomer composition comprisingat least one donor monomer; (b) providing a fluoromonomer compositioncomprising at least one fluoromonomer of the formula F₂C═CXY, where X isCF₃, and Y is either F or CF₃; (c) providing a free radicalpolymerization initiator; (d) adding and mixing the components providedin steps (a), (b), and (c); and (e) polymerizing the monomers atconditions that produce a fluoropolymer wherein units derived from thefluoromonomer and units derived from the donor monomer are distributedalong the fluoropolymer chain in a substantially alternating fashion.

In yet another respect, the present invention is directed to methods forcoating a substrate. These methods of the present invention comprise thesteps of (a) depositing on a substrate a thermosetting composition; (b)coalescing the thermosetting composition to form a substantiallycontinuous film on the substrate; and (c) curing the thermosettingcomposition. In these methods, the thermosetting composition comprises athermosetting composition of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

For purposes of the following detailed description, it is to beunderstood that the invention may assume various alternative variationsand step sequences, except where expressly specified to the contrary. Itis also to be understood that the specific devices and processesdescribed in the following specification are simply exemplaryembodiments of the invention. Hence, any specific dimensions or otherphysical characteristics related to the embodiments disclosed herein arenot to be considered as limiting. Moreover, other than in any operatingexamples, or where otherwise indicated, all numbers expressing, forexample, quantities of ingredients used in the specification and claimsare to be understood as being modified in all instances by the term“about”. Accordingly, unless indicated to the contrary, the numericalparameters set forth in the following specification and attached claimsare approximations that may vary depending upon the desired propertiesto be obtained by the present invention. At the very least, and not asan attempt to limit the application of the doctrine of equivalents tothe scope of the claims, each numerical parameter should at least beconstrued in light of the number of reported significant digits and byapplying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements.

Also, it should be understood that any numerical range recited herein isintended to include all sub-ranges subsumed therein. For example, arange of “1 to 10“is intended to include all sub-ranges between (andincluding) the recited minimum value of 1 and the recited maximum valueof 10, that is, having a minimum value equal to or greater than 1 and amaximum value of equal to or less than 10.

Certain embodiments of the present invention are directed tofluoropolymer compositions. These fluoropolymer compositions comprise(i) units derived from a fluoromonomer of the formula F₂C═CXY, where Xis CF₃ and Y is either F or CF₃; and (ii) units derived from at leastone donor monomer, such as a mild donor monomer.

As used herein, the term “fluoropolymer composition” refers to acomposition that includes a synthesized fluoropolymer as well asresidues from initiators, catalysts, and other elements attendant to thesynthesis of the fluoropolymer. Such residues and other elementsconsidered as part of the fluoropolymer composition are typically mixedor co-mingled with the copolymer such that they tend to remain with thecopolymer when it is transferred between vessels or between solvent ordispersion media.

The fluoropolymers present in the fluoropolymer compositions of thepresent invention comprise units derived from a fluoromonomer having theformula (I)F₂C═CXY  (I)wherein X is CF₃, and Y is either F or CF₃. Specific examples offluoromonomers suitable for use in preparing the fluoropolymercompositions of the present invention include hexafluoropropylene (HFPE)and perfluoroisobutylene (PFIB).

In certain embodiments, the fluoromonomer is present in an amount of to50 mol %, such as 25 to 50 mol %, of the total moles of material presentin the fluoropolymer composition. The level of fluoromonomer used isdetermined by the properties that are to be incorporated into thefluoropolymer composition. The fluoromonomer may be present in thefluoropolymer composition in any range of value inclusive of the recitedvalues.

The fluoropolymers present in the fluoropolymer compositions of thepresent invention also comprise units derived from at least one donormonomer composition, such as a composition comprising a mild donormonomer. As used herein, the term “donor monomer” refers to monomersthat have a polymerizable ethylenically unsaturated group that has arelatively high electron density in the ethylenic double bond. Thisconcept has been quantified to an extent by the Alfrey-Price Q-e scheme(Robert Z. Greenley, Polymer Handbook, Fourth Edition, Brandrup,Immergut and Gulke, editors, Wiley & Sons, New York, N.Y., pp. 309-319(1999)).

The aforementioned fluoromonomers from which the fluoropolymers presentin the fluoropolymer compositions of the present invention are derivedare acceptor monomers. As used herein, the term “acceptor monomer”refers to monomers that have a polymerizable ethylenically unsaturatedgroup that has relatively low electron density in the ethylenic doublebond.

In the Q-e scheme referenced above, Q reflects the reactivity of amonomer and e reflects the polarity of the monomer, which indicates theelectron density of a given monomer's polymerizable ethylenicallyunsaturated group. A positive value for e indicates that a monomer has arelatively low electron density and is an acceptor monomer. A low ornegative value for e indicates that a monomer has a relatively highelectron density and is a donor monomer. All e values recited herein arethose appearing in the Polymer Handbook unless otherwise indicated. Forexample, hexafluoropropylene has a calculated e value of 1.75 based onthe following equation:e value=1.09198−(0.888364*LUMO) −(0.374388*D)wherein LUMO is the energy of the lowest unoccupied molecular orbitaland D is the molecular dipole moment. As those skilled in the art willappreciate, LUMO is a way to measure reductive potential and magnitudeof dipole moment is a measure of the polarity of a compound.

A “strong acceptor monomer” refers to those monomers with an e valuegreater than 2.0. As used herein, the term “mild acceptor monomer”refers to those monomers with an e value greater than 0.5 up to andincluding those monomers with an e value of 2.0. Moreover, as usedherein, the term “strong donor monomer” refers to those monomers with ane value of less than −1.5, while the term “mild donor monomer” refers tothose monomers with an e value of less than 0.5 to those with an e valueof −1.5.

Any suitable donor monomer may be included in the donor monomercomposition used to form the fluoropolymer compositions of the presentinvention, including mixtures of two or more donor monomers. Suitabledonor monomers that may be used include strong donor monomers and, incertain embodiments, mild donor monomers. Specific examples of suitabledonor monomers include, without limitation, ethylene, butene, propylene,styrene, substituted styrenes, α-methyl styrene, isobutylene typemonomers, methacrylate type monomers (such as methyl methacrylate, ethylmethacrylate, propyl methacrylate, isopropyl methacrylate, butylmethacrylate, isopropyl methacrylate, butyl methacrylate, isobutylmethacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, laurylmethacrylate, isobornyl methacrylate, cyclohexyl methacrylate,3,3,5-trimethylcyclohexyl methacrylate, glycidyl methacrylate, andfunctional methacrylates, such as hydroxyalkyl methacrylates, oxiranefunctional methacrylates, and carboxylic acid functional methacrylates),vinyl esters, vinyl pyridines, divinyl benzene, vinyl naphthalene, anddivinyl naphthalene, including mixtures thereof.

In certain embodiments of the present invention, the donor monomercomprises a vinyl ester, an isobutylene type monomer, or a mixturethereof. Suitable vinyl esters include, without limitation, vinyl estersof carboxylic acid, such as vinyl acetate (VAc), vinyl butyrate, vinyl3,4-dimethoxybenzoate, vinyl propionate, vinyl neodecanoate, vinylpivalate, vinyl neononanoate, and vinyl benzoate, including mixturesthereof. In certain embodiments of the present invention, the donormonomer specifically excludes vinyl ether.

As used herein, the term “isobutylene type monomers” refers to donormonomers having the following structure (II):

where R¹ is linear or branched C₁ to C₄ alkyl, and R² is one or more ofmethyl, linear, cyclic or branched C₁ to C₂₀ alkyl, alkenyl, aryl,alkaryl or arakyl.

In certain embodiments, the donor monomer is present in an amount of to50 mol %, such as 50 to 75 mol %, based on the total moles of materialpresent in the fluoropolymer composition. The level of donor monomerused is determined by the properties that are to be incorporated intothe fluoropolymer composition. The donor monomer may be present in thefluoropolymer composition in any range of value inclusive of the recitedvalues.

A non-limiting list of published e values for suitable donor monomersare shown in Table 1. TABLE 1 Alfrey-Price e values for SelectedMonomers Monomer Donor Monomers e value Isobutylene −1.20¹ Diisobutylene 0.49² Vinyl Acetate −0.22¹ Vinyl Pivalate −0.75³ Vinyl Neodecanoate−0.64³ Vinyl Neononanoate −0.48³ α-Methyl Styrene −0.81¹ MethylMethacrylate  0.40¹ Butyl Methacrlyate  0.28¹ Ethyl Methacrylate  0.17¹Glycidyl Methacrylate  0.20¹¹Polymer Handbook, Fourth Edition (1999)²Rzaev et al., Eur. Polym. J., Vol. 24, No. 7, pp. 981-985 (1998)³Polymer Handbook, Second Edition (1975)

As mentioned previously, in the fluoropolymers present in thefluoropolymer compositions of the present invention, the fluoromonomerunits and the donor monomer units are distributed along thefluoropolymer chain in a substantially alternating fashion. As will beappreciated by those skilled in the art, the degree of alternation canbe determined by 13C Fourier Transform Nuclear Magnetic ResonanceSpectroscopy. As used herein, the term “substantially alternating” meansthat most or all of the fluorinated units and donor monomer unitspresent within the fluoropolymer comprise alternating sequences of donormonomer-fluoromonomer pairs, having the alternating monomer residueunits of structure (III):—[DM-FM]—  (III)where DM represents a residue from a donor monomer and FM represents afluorinated unit, i.e., a residue from a fluoromonomer, as opposed toblocks of DM or FM monomeric units. In certain embodiments, thefluoropolymer present in the fluoropolymer compositions of the presentinvention comprises at least 80 mol %, such as at least 90 mol %, or, insome cases, at least 98 mol % of alternating monomer residues asdescribed above. In certain embodiments, the units derived from a donormonomer and a fluoromonomer may be 100% alternating in the fluoropolymerpresent in the fluoropolymer compositions of the present invention. Itis believed that there may be amounts of end groups, and short segments,such as segments having dimer and trimer length, which are not measuredas alternating but are not considered blocks which significantly alterthe properties of the fluoropolymer.

In certain embodiments, the fluoropolymer present in the fluoropolymercompositions of the present invention has a number average molecularweight ranging from 500 to 10,000, such as 750 to 10,000 or, in somecases, 1,000 to 5,000. The molecular weight of the fluoropolymer isselected based on the properties desired to be incorporated into thefluoropolymer composition. The molecular weight of the fluoropolymer mayvary in any range of values inclusive of the recited values.

The polydispersity index (PDI) of the fluoropolymer is not alwayscritical. The PDI of the fluoropolymer is usually less than 4, such asless than 3.0, or, in some cases, less than 2.0. As used herein,“polydispersity index” is determined from the following equation:(weight average molecular weight (Mw)/number average molecular weight(Mn)). A monodisperse polymer has a PDI of 1.0. All of the Mn and Mwvalues reported herein are determined from gel permeation chromatography(GPC) using polystyrene standards.

In certain embodiments of the fluoropolymer compositions of the presentinvention, the fluoropolymer comprises alternating sequences of donormonomer-fluoromonomer residues having the alternating structure (IV):

where X and Y are defined as above.

The fluoropolymer compositions of the present invention may, in certainembodiments, have all of the incorporated monomer residues in analternating architecture. An example of a fluoropolymer compositionsegment having 100% alternating architecture of HFPE and VAc is shown bystructure (V):—VAc—HFPE-VAc—HFPE-VAc—HFPE-VAc—HFPE-VAc—HFPE—  (V)

In certain embodiments, the fluoropolymer composition of the presentinvention may also include other polymerizable ethylenically unsaturatedmonomers, though, in other embodiments, such monomers are not present inany substantial amount (meaning that such other polymerizableethylenically unsaturated monomers are present, if at all, at minor orinconsequential levels that do not significantly effect the propertiesof the fluoropolymer composition). As a result, in the embodimentswherein other polymerizable ethylenically unsaturated monomers arepresent, the fluoropolymer present in the fluoropolymer compositions ofthe present invention may contain alternating segments and randomsegments as shown by structure (VI), a copolymer of HFPE, VAc, and othermonomers, M:

Structure (VI) illustrates certain embodiments of the present inventionwherein the fluoropolymer may include alternating segments as shown inthe boxes and random segments as indicated otherwise.

As illustrated, the random segments of the fluoropolymer may containdonor or acceptor monomer residues that have not been incorporated intothe fluoropolymer composition by way of an alternating architecture.These random segments of certain embodiments of the fluoropolymercomposition may include residues from the other ethylenicallyunsaturated monomers mentioned earlier. All references herein to polymersegments derived from alternating segments of donormonomer-fluoromonomer pairs are meant to include segments of monomerresidues such as those shown by the boxes in structure (VI). Residuesfrom other ethylenically unsaturated monomer may comprise residues fromany suitable monomer not traditionally categorized as being an acceptormonomer or a donor monomer.

The residues from the other ethylenically unsaturated monomers, residueM of structure (VI), are derived from at least one ethylenicallyunsaturated radically polymerizable monomer. As used herein, the term“ethylenically unsaturated radically polymerizable monomer” and liketerms is meant to include vinyl monomers, allylic monomers, olefins, andother ethylenically unsaturated monomers that are radicallypolymerizable and not classified as donor monomers or acceptor monomers.

As used herein, the term “allylic monomer(s)” refers to monomerscontaining substituted and/or unsubstituted allylic functionality, i.e.,one or more radicals represented by the following general formula (VI):H₂C═C(R)—CH₂—  (VI )where R is hydrogen, halogen, or a C₁ to C₄ alkyl group. Often, R ishydrogen or methyl, and, consequently, general formula (VII) oftenrepresents the unsubstituted (meth)allyl radical, which encompasses bothallyl and methallyl radicals. Examples of allylic monomers include,without limitation, (meth)allyl alcohol, (meth)allyl ethers, such asmethyl (meth)allyl ether; allyl esters of carboxylic acids, such as(meth)allyl acetate, (meth)allyl butyrate, and (meth)allyl benzoate.

In certain embodiments, the fluoropolymer compositions of the presentinvention may include other acceptor monomers, aside from thefluoromonomers described above. Suitable other acceptor monomers includethose disclosed in U.S. Pat. No. 6,686,432 at col. 7, line 39 to col. 8,line 67, which is incorporated herein by reference. In certainembodiments, the fluoropolymer compositions of the present invention aresubstantially free of such other acceptor monomers (meaning that suchother acceptor monomers are present, if at all, at minor orinconsequential levels that do not significantly effect the propertiesof the fluoropolymer composition).

The present invention is also directed to methods of makingfluoropolymer compositions. The fluoropolymer compositions of thepresent invention can be prepared by methods that include the steps of(a) providing a donor monomer composition comprising at least one donormonomer; (b) providing a fluoromonomer composition comprising at leastone fluoromonomer of the formula F₂C═CXY, where X is CF₃, and Y iseither F or CF₃; (c) providing a free radical polymerization initiator;(d) mixing the components provided in steps (a), (b), and (c); and (e)polymerizing the monomers at conditions that produce a fluoropolymerwherein units derived from the fluoromonomer and units derived from thedonor monomer are distributed along the fluoropolymer chain in asubstantially alternating fashion.

In these methods of the present invention, the donor monomer, thefluoromonomer, and the free radical polymerization initiator are mixedtogether, such as by separately and simultaneously adding and mixingthem together in a reaction vessel. In certain embodiments, the donormonomer, the fluoromonomer and the initiator are added at rates suchthat each of their respective additions is completed in about the sametime period. For example, each of these components may be added over aperiod of at least 15 minutes, in some cases at least 20 minutes, inother cases at least 30 minutes, and, in some cases, at least 1 hour. Incertain embodiments, the addition time is not so long as to render theprocess economically unfeasible on a commercial scale. The addition timemay vary in any range of values inclusive of those stated above.

In other embodiments, the donor monomer, the fluoromonomer, and the freeradical polymerization initiator are mixed together by separately andsimultaneously adding the donor monomer and the free radicalpolymerization initiator together to a reaction vessel containing thefluoromonomer. In certain embodiments, the donor monomer and theinitiator are added at rates such that each of their respectiveadditions is completed in about the same time period. For example, eachof these components may be added over a period of at least 15 minutes,in some cases at least 20 minutes, in other cases at least 30 minutes,and, in some cases, at least 1 hour. In certain embodiments, theaddition time is not so long as to render the process economicallyunfeasible on a commercial scale. The addition time may vary in anyrange of values inclusive of those stated above.

In certain embodiments of the methods of the present invention, the moleratio of fluoromonomer to donor monomer that is added is at least 1:2.The mole ratio of fluoromonomer to donor monomer that is added to themixture is selected based on the properties desired to be incorporatedinto the fluoropolymer composition.

After mixing or during addition and mixing, polymerization of themonomers takes place. In the methods of the present invention, thepolymerization may be conducted at any suitable temperature that resultsin a fluoropolymer wherein the fluoromonomer units and the donor monomerunits are distributed along the fluoropolymer chain in a substantiallyalternating fashion. Suitable temperatures include ambient, 50° C. to300° C., 60° C. to 275° C., 75° C. to 250° C., or 100° C. to 225° C. Thetemperature is typically high enough to encourage good reactivity fromthe monomers and initiators employed. However, the volatility of themonomers and corresponding partial pressures create a practical upperlimit on temperature determined by the pressure rating of the reactionvessel. The polymerization temperature may vary in any range of valuesinclusive of those stated above.

In the methods of the present invention, the polymerization may beconducted at any suitable pressure. Suitable pressures may be up to 2000psi, up to 1000 psi, up to 600 psi, or, in some cases, 100 psi to 600psi. The pressure is typically high enough to maintain the monomers as asupercritical fluid. The pressures employed have a practical upper limitbased on the pressure rating of the reaction vessel employed. Thepressure during polymerization temperature may vary in any range ofvalues inclusive of those stated above.

Any suitable free radical initiator may be used in the methods of makingfluoropolymer compositions of the present invention. Examples ofsuitable free radical initiators include, without limitation, thermalfree radical initiators, photo-initiators, and redox initiators.Examples of suitable thermal free radical initiators include, withoutlimitation, peroxide compounds, azo compounds, and persulfate compounds.

Examples of suitable peroxide compound initiators include, withoutlimitation, hydrogen peroxide, methyl ethyl ketone peroxides, benzoylperoxides, di-t-butyl peroxide, di-t-amyl peroxide, dicumyl peroxide,diacyl peroxides, decanoyl peroxides, lauroyl peroxides,peroxydicarbonates, peroxyesters, dialkyl peroxides, hydroperoxides,peroxyketals, and mixtures thereof.

Examples of suitable azo compounds include, but are not limited to,4-4′-azobis(4-cyanovaleric acid), 1-1′-azobiscyclohexanecarbonitrile,2-2′-azobisisobutyronitrile,2-2′-azobis(2-methylpropionamidine)dihydrochloride,2-2′-azobis(2-methylbutyronitrile), 2-2′-azobis(propionitrile),2-2′-azobis(2,4-dimethylvaleronitrile), 2-2′-azobis(valeronitrile),2,2′-azobis[2-methyl-N-(2-hydroxyethyl)propionamide],4,4′-azobis(4-cyanopentanoic acid),2,2′-azobis(N,N′-dimethyleneisobutyramidine),2,2′-azobis(2-amidinopropane)dihydrochloride,2,2′-azobis(N,N′-dimethyleneisobutyramidine)dihydrochloride, and2-(carbamoylazo)-isobutyronitrile.

In certain embodiments, the fluoropolymer of the present invention maybe utilized as a starting material for the preparation of functionalgroup containing polymers by using functional group transformations bymethods known in the art. Functional groups that can be introduced tothe fluoropolymers include epoxy, carboxylic acid, hydroxy, amide,oxazoline, acetoacetate, isocyanate, carbamate, amine, amine salt,quaternary ammonium, thioether, sulfide, sulfonium and phosphate groups,among others. Suitable methods for introducing such functional groups tothe fluoropolymers of the present invention include methods described inU.S. Pat. No. 6,686,432B2 at col. 13, line 16 to col. 14, line 26, whichis incorporated herein by reference.

In certain embodiments, such as in the case where the fluoropolymer ofthe present invention is derived from a fluoromonomer and a vinyl ester,such as vinyl acetate, such a fluoropolymer may be partially orcompletely transesterified to form a corresponding fluoropolymer offluoromonomer/vinyl alcohol or fluoromonomer/vinyl alcohol/vinyl ester.Such a transesterification may be conducted by any suitable means. Forexample, the transesterification of the fluoropolymer may be conductedby dissolving the fluoropolymer in a suitable solvent, such as methanol,in the presence of a suitable base, such as sodium methoxide, potassiumcarbonate, or lithium carbonate, or a suitable acid catalyst, such asp-toluenesulfonic acid, sulfuric acid, or a Lewis acid, and removing lowmolecular weight esters, such as methyl acetate. In certain embodiments,at least 25 percent of the fluoropolymer is transesterified as describedabove.

The present invention is also directed to thermosetting compositions. Asused herein, the term “thermosefting” refers to polymeric compositionsthat “set” irreversibly upon curing or crosslinking, wherein the polymerchains of the polymeric components are joined together by covalentbonds. This property is usually associated with a cross-linking reactionof the composition constituents often induced, for example, by heat orradiation. See Hawley, Gessner G., The Condensed Chemical Dictionary,Ninth Edition., page 856; Surface Coatings, vol. 2, Oil and ColourChemists' Association, Australia, TAFE Educational Books (1974). Curingor crosslinking reactions also may be carried out under ambientconditions. Once cured or crosslinked, a thermosetting resin will notmelt upon the application of heat and is insoluble in solvents.

As used herein, the term “cure” means that any crosslinkable componentsof the composition are at least partially crosslinked. In certainembodiments, the crosslink density of the crosslinkable components,i.e., the degree of crosslinking, ranges from 5% to 100% of completecrosslinking, such as 35% to 85% of complete crosslinking. One skilledin the art will understand that the presence and degree of crosslinking,i.e., the crosslink density, can be determined by a variety of methods,such as dynamic mechanical thermal analysis (DMTA) using a PolymerLaboratories MK III DMTA analyzer conducted under nitrogen. This methoddetermines the glass transition temperature and crosslink density offree films of coatings or polymers. These physical properties of a curedmaterial are related to the structure of the crosslinked network.

According to this method, the length, width, and thickness of a sampleto be analyzed are first measured, the sample is tightly mounted to thePolymer Laboratories MK III apparatus, and the dimensional measurementsare entered into the apparatus. A thermal scan is run at a heating rateof 3° C. per minute, a frequency of 1 Hz, a strain of 120%, and a staticforce of 0.01 N, and sample measurements occur every two seconds. Themode of deformation, glass transition temperature, and crosslink densityof the sample can be determined according to this method. Highercrosslink density values indicate a higher degree of crosslinking in thecoating.

The thermosetting compositions of the present invention may be in theform of liquid coating compositions, examples of which include aqueousand solvent-based coating compositions and electrodepositable coatingcompositions. The thermosetting compositions of the present inventionmay also be in the form of a co-reactable solid in particulate form,such as a powder coating composition. Regardless of the form, thethermosetting compositions of the present invention may be pigmented orclear, and may be used alone or in combination as primers, basecoats, ortopcoats.

The thermosetting compositions of the present invention include: (a) atleast one reactive functional group containing fluoropolymer of the typedescribed earlier, and (b) at least one crosslinking agent thatcomprises at least two functional groups reactive with the functionalgroups of the fluoropolymer.

The fluoropolymer compositions described earlier may be used in thethermosetting composition of the present invention as a resinous binderor as an additive in combination with a separate resinous binder. Whenused as an additive, the fluoropolymer compositions as described hereinmay have low functionality (they may be monofunctional) and have acorrespondingly high equivalent weight. Alternatively, for otherapplications such as use as a reactive diluent, the additive may behighly functional with a correspondingly low equivalent weight.

In certain embodiments, the fluoropolymer is present in thethermosetting coating composition in an amount of up to 80 weightpercent, such as 20 to 80 weight percent, 40 to 80 weight percent, or,in some cases, 50 to 80 weight percent, with weight percent being basedon the total solid weight of the composition. The fluoropolymer may bepresent in the thermosetting composition in an amount ranging betweenany combination of these values, inclusive of the recited values.

As previously indicated, the thermosetting compositions of the presentinvention comprise a crosslinking agent having at least two functionalgroups that are reactive with functional groups of the fluoropolymer.Not wishing to be limited to any one set of functional groups, there areseveral examples of co-reactive functional groups that can be used inthe thermosetting compositions of the present invention. For example,the functional groups of the first reactant, i.e., the fluoropolymer,may comprise any of the functional groups identified earlier, amongothers, and the functional groups of the second reactant, i.e., thecrosslinking agent, may comprise any functional group that is differentfrom the functional groups contained in the fluoropolymer and that isco-reactive towards the functional groups of the fluoropolymer reactant.

Crosslinking agents suitable for use in the thermosetting compositionsof the present invention include aminoplast resins, phenoplast resins,and mixtures thereof, as curing agents for hydroxy, carboxylic acid,amide, and carbamate functional group containing materials. Examples ofaminoplast and phenoplast resins suitable for use as crosslinking agentsin certain thermosetting compositions of the present invention includethose described in U.S. Pat. No. 3,919,351 and col. 5, line 22 to col.6, line 25, which is incorporated herein by reference.

Polyisocyanates and blocked polyisocyanates are also suitable for use ascrosslinking agents in certain thermosetting compositions of the presentinvention, such as when the fluoropolymer described above compriseshydroxy functional groups or primary and/or secondary amino groups.Examples of polyisocyanates and blocked isocyanates suitable for use ascrosslinking agents in certain thermosetting compositions of the presentinvention include those described in U.S. Pat. No. 4,546,045 at col. 5,lines 16 to 38 and U.S. Pat. No. 5,468,802 at col. 3, lines 48 to 60,both of which are incorporated herein by reference.

Anhydrides as crosslinking agents for hydroxy and primary and/orsecondary amino group containing materials are also suitable for use incertain thermosetting compositions of the present invention and areknown in the art. Examples of anhydrides suitable for use ascrosslinking agents in certain compositions of the present inventioninclude those described in U.S. Pat. No.4,798,746 at col. 10, lines 16to 50 and U.S. Pat. No. 4,732,790 at col. 3, lines 41 to 57, both ofwhich are incorporated herein by reference.

Polyepoxides as crosslinking agents for carboxylic acid functional groupcontaining materials are suitable for use in certain thermosettingcompositions of the present invention and are known in the art. Examplesof polyepoxides suitable for use as crosslinking agents in certaincompositions of the present invention include those described in U.S.Pat. No. 4,681,811 at col. 5, lines 33 to 58, which is incorporatedherein by reference.

Polyacids as crosslinking agents for epoxy functional group containingmaterials are suitable for use in certain thermosetting compositions ofthe present invention and are known in the art. Examples of polyacidssuitable for use as crosslihking agents in certain compositions of thepresent invention include those described in U.S. Pat. No. 4,681,811 atcol. 6, line 45 to col. 9, line 54, which is incorporated herein byreference.

Polyols, that is, material having an average of two or more hydroxylgroups per molecule, are known in the art for use as crosslinking agentsfor isocyanate functional group containing materials and anhydrides andesters. Polyacids are suitable for use as crosslinking agents in certaincompositions of the present invention, including those described in U.S.Pat. No. 4,046,729 at col. 7, line 52 to col. 8, line 9; col. 8, line 29to col. 9, line 66; and in U.S. Pat. No. 3,919,315 at col. 2, line 64 tocol. 3, line 33, both of which are incorporated herein by reference.

Polyamines as crosslinking agents for isocyanate functional groupcontaining materials and for carbonates and unhindered esters aresuitable for use in certain compositions of the present invention andare known in the art. Examples of polyamines suitable for use ascrosslinking agents in certain compositions of the present inventioninclude those described in U.S. Pat. No. 4,046,729 at col. 6, line 61 tocol. 7, line 26, which is incorporated herein by reference.

When desired, appropriate mixtures of crosslinking agents may be used.Moreover, the thermosetting compositions of the present invention can beformulated as a one-component composition where a crosslinking agent,such as an aminoplast resin and/or a blocked isocyanate compound, suchas those described above, is admixed with other composition components.Such one-component compositions can be storage stable as formulated.Alternatively, compositions may be formulated as two-componentcompositions where, for example, a polyisocyanate crosslinking agent,such as those described above, can be added to a pre-formed admixture ofthe other composition components just prior to application. Thepre-formed admixture may comprise crosslinking agents, such asaminoplast resins and/or blocked isocyanate compounds, such as thosedescribed earlier.

In certain embodiments, the crosslinking agent is present in thethermosetting composition in an amount of up to 40 weight percent, suchas 20 to 40 weight percent, with weight percent being based on the totalsolid weight of the coating composition. The amount of crosslinkingagent present in the thermosetting composition of the present inventionmay range between any combination of these values, inclusive of therecited values.

In certain embodiments, wherein the fluoropolymer comprises hydroxylfunctional groups, the equivalent ratio of hydroxyl groups in thefluoropolymer to reactive functional groups in the crosslinking agentmay be within the range of 1:0.5 to 1:1.5, such as 1:0.8 to 1:1.2.

As mentioned earlier, the fluoropolymer compositions described earliermay be used in the thermosetting compositions of the present inventionas an additive in combination with a separate resinous binder. Suitableresinous binders that may be used in the thermosetting compositions ofthe present invention, in addition to the fluoropolymer compositions,include, hydroxyl or carboxylic acid-containing acrylic copolymers,hydroxyl or carboxylic acid-containing polyester polymers and oligomers,isocyanate or hydroxyl-containing polyurethane polymers, and/or amine orisocyanate-containing polyureas, among others.

Acrylic polymers, if used, are typically copolymers of acrylic acid ormethacrylic acid or hydroxyalkyl esters of acrylic or methacrylic acidsuch as hydroxyethyl methacrylate or hydroxypropyl acrylate with one ormore other polymerizable ethylenically unsaturated monomers such asalkyl esters of acrylic acid including methyl methacrylate and 2-ethylhexyl acrylate, and vinyl aromatic compounds such as styrene,alpha-methyl styrene and vinyl toluene. The ratio of reactants andreaction conditions are selected to result in an acrylic polymer withpendant hydroxyl or carboxylic acid functionality.

Besides acrylic polymers, a polyester polymer or oligomer may be used.Such polymers may be prepared in a known manner by condensation ofpolyhydric alcohols and polycarboxylic acids. Suitable polyhydricalcohols include, for example, ethylene glycol, neopentyl glycol,trimethylol propane and pentaerythritol.

Suitable polycarboxylic acids include, for example, adipic acid,1,4-cyclohexyl dicarboxylic acid and hexahydrophthalic acid. Besides thepolycarboxylic acids mentioned above, functional equivalents of theacids such as anhydrides where they exist or lower alkyl esters of theacids such as the methyl esters may be used. Also, small amounts ofmonocarboxylic acids such as stearic acid may be used.

Hydroxyl-containing polyester oligomers can be prepared by reacting ananhydride of a dicarboxylic acid such as hexahydrophthalic anhydridewith a diol such as neopentyl glycol in a 1:2 molar ratio.

Where it is desired to enhance air-drying, suitable drying oil faftyacids may be used and include, for example, those derived from linseedoil, soya bean oil, tall oil, dehydrated castor oil or tung oil, amongothers.

Polyurethane polymers containing terminal isocyanate or hydroxyl groupsmay also be used. Polyurethane polyols or NCO-terminated polyurethanesthat can be used include, for example, those prepared by reactingpolyols including polymeric polyols with polyisocyanates. Thepolyurea-containing terminal isocyanate or primary or secondary aminegroups which can be used include, for example, those prepared byreacting polyamines including polymeric polyamines with polyisocyanates.The hydroxyl/isocyanate or amine/isocyanate equivalent ratio is adjustedand reaction conditions selected to obtain the desired terminal group.Examples of suitable polyisocyanates include those described in U.S.Pat. No. 4,046,729 at column 5, line 26 to column 6, line 28,incorporated herein by reference. Examples of suitable polyols includethose described in U.S. Pat. No. 4,046,729 at column 7, line 52 tocolumn 10, line 35, incorporated herein by reference. Examples ofsuitable polyamines include those described in U.S. Pat. No. 4,046,729at column 6, line 61 to column 7, line 32 and in U.S. Pat. No. 3,799,854at column 3, lines 13 to 50, both incorporated herein by reference.

In certain embodiments, the thermosetting compositions of the presentinvention also contain catalysts to accelerate the cure of thecrosslinking agent with reactive groups on the fluoropolymer(s).Suitable catalysts for aminoplast cure include acids, such as acidphosphates and sulfonic acid or a substituted sulfonic acid. Examplesinclude dodecylbenzene sulfonic acid, paratoluene sulfonic acid, phenylacid phosphate, ethylhexyl acid phosphate, and the like. Suitablecatalysts for isocyanate cure include organotin compounds such asdibutyltin oxide, dioctyltin oxide, dibutyltin dilaurate, and the like.In certain embodiments of the present invention, the catalyst is presentin the thermosetting composition in an amount of 0.05 to 5.0 percent byweight, such as 0.25 to 2.0 percent by weight, based on the total weightof resin solids in the thermosetting composition.

In certain embodiments, the thermosetting compositions of the presentinvention are used as film-forming (coating) compositions, and maycontain adjunct ingredients conventionally used in such compositions.Optional ingredients such as, for example, plasticizers, surfactants,thixotropic agents, anti-gassing agents, organic cosolvents, flowcontrollers, anti-oxidants, UV light absorbers and similar additivesconventional in the art may be included in the composition. Any suchadditives known in the art can be used, absent compatibility problems.Nonlimiting examples of these materials are described in U.S. Pat. Nos.4,220,679; 4,403,003; 4,147,769; and 5,071,904. In some cases, theseingredients are present at up to 40 percent by weight based on the totalweight of resin solids in the thermosetting composition.

As previously mentioned, the thermosetting compositions of the presentinvention may be in the form of liquid compositions, that is, waterborneor solventborne systems, wherein the components of the thermosettingcomposition are dispersed in a diluent. Suitable diluents includeorganic solvents, water, and/or water/organic solvent mixtures.

In some cases, the liquid thermosetting compositions of the presentinvention are in the form of solventborne systems. Suitable organicsolvents include, for example, alcohols, ketones, aromatic hydrocarbons,glycol ethers, esters or mixtures thereof.

In some cases, the thermosetting compositions of the present inventionare in the form of waterborne systems. In these embodiments, thecomposition is in the form of an aqueous dispersion. The term“dispersion” refers to a two-phase transparent, translucent, or opaqueresinous system in which the resin is in the dispersed phase and thewater is in the continuous phase. The average particle size of theresinous phase is generally less than 1.0 micron, such as less than 0.5micron, or less than 0.1 micron.

One advantage of the fluoropolymers of the present invention is that,because they can be of relatively low molecular weight, they can be usedin thermosetting coating compositions that contain relatively highsolids content, which is often desirable for many reasons that will beapparent to those skilled in the art. In certain embodiments, whereinthe thermosetting composition is a liquid thermosetting composition, thecompositions comprise at least 40 weight percent, such at least 70weight percent, or, in some cases, at least 90 weight percent solids,i.e., non-volatiles, with weight percent being based on the total weightof the composition. In these embodiments, the solids may be present inthe thermosetting composition in any range of value inclusive of therecited values.

In addition to the components described above, the thermosettingcompositions of the present invention may also contain color pigments,such as those conventionally used in surface coatings and may be used asa monocoat, that is, a pigmented coating. The suitability of using aparticular pigment will be apparent to those skilled in the art.Suitable pigments include, for example, inorganic, organic, metallic,metallic-effect, and anti-corrosive pigments, including mixturesthereof.

Specific examples of suitable inorganic pigments include, withoutlimitation, titanium dioxide, iron oxides, lead chromate, chromiumoxide, chrome green, cadmium sulfide, lithopone pigments, and the like.Specific examples of suitable organic pigments include, withoutlimitation, carbon black; monoazo, diazo, and benzimidazolone yellows,oranges, reds, and browns; phthalocyanine blues and greens;anthraquinone pigments ranging from yellow to blue; quinacridoneyellows, reds, and violets; perylene reds and browns; indigoid reds,blues, and violets; thionidigo violets; isoindolinone yellows, orangesand reds; quinoline yellows, among others. Specific examples of suitablemetallic pigments include, without limitation, aluminum zinc, lead,bronze, copper, stainless steel, and mica, nickel and tin flakes, amongothers. Specific examples of suitable anti-corrosive pigments include,without limitation, lead oxide, zinc chromate, zinc phosphate, micaceousiron oxide, among others.

In certain embodiments, the pigment is incorporated into thethermosetting composition in amounts of up to 80 percent by weight,based on the total weight of solids in the composition. The metallicpigment is, in certain embodiments, employed in amounts of 0.5 to 25percent by weight based on the total weight of solids in thecomposition. In these embodiments, the pigment may be present in thethermosetting composition in any range of values inclusive of therecited values.

As stated above, the thermosetting compositions of the present inventionmay be used in a method of coating a substrate comprising applying athermosetting composition to the substrate, coalescing the thermosettingcomposition over the substrate in the form of a substantially continuousfilm, and curing the thermosetting composition.

The thermosetting compositions of the present invention can be appliedto various substrates to which they adhere including wood, metals,glass, paper, masonry surfaces, and plastic, among others. Thecompositions can be applied by conventional means including brushing,dipping, flow coating, spraying and the like, but they are most oftenapplied by spraying. The usual spray techniques and equipment for airspraying and electrostatic spraying and either manual or automaticmethods can be used.

After application of the composition to the substrate, the compositionis allowed to coalesce to form a substantially continuous film on thesubstrate. Typically, the film thickness will be 0.01 to 5 mils (0.25 to127 microns), such as 0.1 to 2 mils (2.54 to 50.8 microns) in thickness.The film is formed on the surface of the substrate by driving solvent,i.e., organic solvent and/or water, out of the film by heating or by anair drying period. In some cases, the heating will only be for a shortperiod of time, sufficient to ensure that any subsequently appliedcoatings can be applied to the film without dissolving the composition.Suitable drying conditions will depend on the particular composition,but, in general, a drying time of from 1 to 5 minutes at a temperatureof 68° F. to 250° F. (20° C. to 121° C.) will be adequate. More than onecoat of the composition may be applied to develop the optimumappearance. Between coats the previously applied coat may be flashed,that is, exposed to ambient conditions for 1 to 20 minutes.

The thermosetting compositions of the present invention may be used aspart of a multi-layer composite coating composition, such as a“color-plus-clear” coating system, which includes at least one pigmentedor colored base coat and at least one clear topcoat. As a result, thepresent invention is also directed to multi-layer composite coatings,wherein at least one coating layer is deposited from a compositioncomprising a thermosetting composition of the present invention.

For example, the clear film-forming composition may include thethermosetting composition of the present invention. In such embodiments,the film-forming composition of the base coat in the color-plus-clearsystem may comprise any composition useful in coatings applications,such as those typically used in automotive OEM applications, automotiverefinish applications, industrial coating applications, architecturalcoating applications, electrocoating applications, powder coatingapplications, coil coating applications, and aerospace coatingapplications, among others. The film-forming composition of the basecoat typically comprises a resinous binder and a pigment to act as thecolorant. Particularly useful resinous binders include theafore-mentioned acrylic polymers, polyesters, including alkyds, andpolyurethanes, among others.

The base coat compositions may be solvent borne or waterborne. Suitablewaterborne base coats in color-plus-clear compositions include thosedisclosed in U.S. Pat. No. 4,403,003, and the resinous compositions usedin preparing these base coats can be used in the practice of themulti-layer composite coatings of the present invention. Also,waterborne polyurethanes such as those prepared in accordance with U.S.Pat. No. 4,147,679 can be used as the resinous binder in the base coat.Further, waterborne coatings such as those described in U.S. Pat. No.5,071,904 can be used as the base coat.

If desired, the base coat composition may contain additional materialswell known in the art of formulated surface coatings, including thosediscussed above. These materials can constitute up to 40 percent byweight of the total weight of the coating composition.

The base coating compositions can be applied to various substrates towhich they adhere by conventional means, but they are most often appliedby spraying. The usual spray techniques and equipment for air sprayingand electrostatic spraying and either manual or automatic methods can beused.

During application of the base coat composition to the substrate, a filmof the base coat is formed on the substrate. Typically, the base coatthickness will be 0.01 to 5 mils (0.25 to 127 microns), preferably 0.1to 2 mils (2.54 to 50.8 microns) in thickness.

After application of the base coat to the substrate, a film is formed onthe surface of the substrate by driving solvent out of the base coatfilm, by heating or by an air drying period, sufficient to ensure thatthe clear coat can be applied to the base coat without the formerdissolving the base coat composition, yet insufficient to fully cure thebase coat. More than one base coat and multiple clear coats may beapplied to develop the optimum appearance. Usually between coats, thepreviously applied coat is flashed.

The clear topcoat composition may be applied to the base coatedsubstrate by any conventional coating technique, such as brushing,spraying, dipping or flowing, but spray applications are often preferredbecause of superior gloss. Any of the known spraying techniques may beemployed, such as compressed air spraying, electrostatic spraying, andeither manual or automatic methods.

After application of the clear coat composition to the base coat, thecoated substrate may be heated to cure the coating layer(s). In thecuring operation, solvents are driven off and the film-forming materialsin the composition are crosslinked. The heating or curing operation isusually carried out at a temperature in the range of from at leastambient (in the case of free polyisocyanate crosslinking agents) to 350°F. (ambient to 177° C.) but, if needed, lower or higher temperatures maybe used as necessary to activate crosslinking mechanisms.

In certain embodiments, the thermosetting compositions of the presentinvention can be applied through electrodeposition. In such cases, thecompositions include active hydrogen group-containing polymers. Theactive hydrogen-containing polymer typically has a suitable ionic group,such as anionic and cationic groups. Suitable cationic groups include,but are not limited to onium salt groups.

The active hydrogen group-containing polymer containing onium saltgroups may be present in the thermosetting compositions of the inventionas a resinous binder (i.e., a film-forming polymer) or as an additive incombination with a separate resinous binder. When used as an additive,for example, as a reactive diluent, the active hydrogen group-containingpolymer has a high degree of functionality and a correspondingly lowequivalent weight. However, it should be appreciated that for otherapplications, the additive may have low functionality (it may bemonofunctional) and a correspondingly high equivalent weight.

In certain embodiments, the electrodeposition coating composition willtypically include (a) a first reactant having functional groups, (b) asecond reactant that is a crosslinking agent having functional groupsthat are co-reactive towards and can form covalent bonds with thefunctional groups of the first reactant. The first and second reactantsof the electrodeposition coating composition may each independentlycomprise one or more functional species as discussed above with regardto liquid and powder coating compositions.

In some embodiments, the thermosetting compositions of the presentinvention can be in the form of electrodeposition baths. Such baths areoften supplied as two components, (1) a clear feed resin, which oftenincludes an active hydrogen-containing polymer, such as thefluoropolymer disclosed herein, which contains onium salt groups, i.e.,the main film-forming polymer, the crosslinking agent, and anyadditional water-dispersible, non-pigmented components, and (2) apigment paste, which often includes one or more pigments, awater-dispersible grind resin which can be the same or different fromthe main film-forming polymer, and, optionally, additives or dispersingaids. Electrodeposition baths (1) and (2) are dispersed in an aqueousmedium which comprises water and, often, coalescing solvents. In somecases, the electrodeposition bath may be supplied as a one-componentsystem that contains the main film-forming polymer, the crosslinkingagent, the pigment paste, and any optional additives in one package.Such one-component systems are dispersed in an aqueous medium asdescribed above. The electrodeposition baths usually have a resin solidscontent within the range of 10 to 25 percent by weight based on thetotal weight of the electrodeposition bath.

As mentioned above, the aqueous medium of the electrodeposition baths(1) and (2) may comprise a coalescing solvent in addition to water.Useful coalescing solvents include hydrocarbons, alcohols, esters,ethers, and ketones. Specific examples of suitable coalescing solventsinclude, without limitation, isopropanol, butanol, 2-ethylhexanol,isophorone, 2-methoxypentanone, ethylene, and propylene glycol,including the monoethyl, monobutyl, and monohexyl ethers or ethylene orpropylene glycol. The amount of coalescing solvent is generally between0.01 and 25 percent, such as 0.05 to 5 percent, by weight based on thetotal weight of the aqueous medium.

A pigment composition and, if desired, various additives, such assurfactants, wetting agents, or catalyst, can be included in thedispersion. The pigment composition may be of the conventional type,comprising pigments, such as iron oxides, strontium chromate, carbonblack, coal dust, titanium dioxide, talc, barium sulfate, and colorpigments, such as cadmium yellow, cadmium red, chromium yellow, and thelike, among others. The pigment content of the dispersed is oftenexpressed as a pigment-to-resin ratio, and, such a ratio is often in therange of 0.02 to 1:1. The other additives, if used, are often in thedispersion in amounts of 0.01 to 3 percent by weight based on weight ofresin solids.

The thermosetting compositions of the present invention may, in certainembodiments, by applied to a substrate by electrodeposition to a varietyof electro-conductive substrate, such as metals, including untreatedsteel, galvanized steel, aluminum, copper, magnesium, and conductivecarbon coated materials. The applied voltage for electrodeposition maybe varied and can be, for example, as low as 1 volt to as high asseveral thousand volts, such as between 50 and 500 volts. The currentdensity is often between 0.5 ampere and 5 ampere per square foot andtends to decrease during electrodeposition indicating the formation ofan insulating film.

After the coating has been applied by electrodeposition, it is cured,often by baking at elevated temperatures, such as 90° C. to 260° C., for1 minute to 40 minutes.

Illustrating the invention are the following examples, which, however,are not to be considered as limiting the invention to their details.Unless otherwise indicated, all parts and percentages in the followingexamples, as well as throughout the specification, are by weight.

EXAMPLES Example 1 Synthesis of HFPE-Vinyl Acetate Copolymer

A copolymer of HFPE and vinyl acetate was polymerized from theingredients listed in Table 1 and the procedure set forth below. TABLE 2Ingredients Parts by Weight (Grams) Charge 1 Toluene 150 Charge 2Di-t-amyl Peroxide 27.5 Charge 3 Hexafluoropropylene 349 Charge 4 VinylAcetate 200

Charge 1 and 3 was added to a stainless steel pressure reaction vesselequipped with an agitator, a thermocouple, and a nitrogen inlet, placedunder a 5 psig nitrogen pad, and heated to 140° C. Charge 2 and 4 wereadded over 2.5 hours maintaining temperature at 140° C. at a finalpressure of 125 psig. After the additions of Charges 2 through 4 werecompleted the reaction mixture was held for 2 hours at 170° C. Thereaction mixture was then cooled to ambient temperature.

The measured solids were 78.1 weight percent at 110° C. for 1 hour. Thecopolymer had an Mn of 2400 and an Mw/Mn of 1.7 (determined by gelpermeation chromatography using Evaporative Light-scaftering Detector).The NMR spectrum was consistent with a copolymer composition comprising51% molar vinyl acetate and 49% molar hexafluoropropylene. The monomerdistribution was determined by 13C Fourier Transform Nuclear MagneticResonance Spectroscopy (“NMR”) and the degree of alternation of monomerresidues of CTFE and vinyl acetate was 98 mol %.

Example 2 Hydrolysis of HFPE-Vinyl Acetate Copolymer from Example 1

The following ingredients were added to a one-liter, four-neckedreaction vessel equipped with a thermometer, stirrer, nitrogen inlet,and means for removing the reaction by-product (methyl acetate): 200grams of copolymer HFPE-vinyl acetate of Example 1 above; 50 grams ofmethanol. The reaction mixture was heated to 57° C. and 2.0 grams oflithium carbonate and 2.0 grams potassium carbonate were added. Thereaction mixture was held at that temperature for 5 hours, and 2.3 gramsof potassium carbonate were added, and the reaction mixture was held for5 hours. The catalyst was removed by filtration through Magnesol cake.The excess methanol was striped. The sample analyzed by NMR indicatedthat 100% vinyl acetate was converted to vinyl alcohol.

Example 3 Preparation of Coating Compositions Example 3A

A coating composition was prepared by combining 60 grams of HFPE-vinylalcohol copolymer of Example 2 with 40 grams of melamine Cymel 202(melamine commercially available from Cytec Industries, Inc.), 300 g ofDowanol PM (glycol ether commercially available from Dow Chemical Co.),and 1 gram of dodecylbenzene sulfonic acid as catalyst. The mixture wasdrawn down 3 mil thick over an electrodeposition primer coated steelpanel (cold rolled steel panels 4″×12″, available as APR4128 from ACTLaboratories, Inc., Hillsdale, Michigan). The drawn down coating layerwas baked for 30 minutes at 140° C.

Acetone rub solvent resistance was used to determine the cure of thepaint. Cheesecloth was moistened with acetone and, with moderatepressure, at a rate of about 1 double rub per second, rubbed over thepainted panel. This test is typically run to 100 double rubs or failureof the coating, which ever occurs first. The higher the number of rubs,the better the cure of the coating. The cured film resulting fromExample 3A was hard and did not fail after 100 double rubs with acetone.

Example 3B

A coating composition was prepared by combining 60 grams of HFPE-vinylalcohol copolymer of Example 2 with 21 grams of Desmodur N3390(polyisocyanate commercially available from Bayer Material Science,Pittsburgh, Pennsylvania), 300 grams of butyl acetate, and 1 gram ofdibutyltindilaurate as catalyst. The mixture was drawn down 3 mil thickover an electrodeposition primer coated steel panel (cold rolled steelpanels 4″×12″, available as APR4128 from ACT Laboratories, Inc.,Hillsdale, Mich.). The drawn down coating layer was baked for 30 minutesat 140° C. The cured film resulting from Example 3B was hard and did notfail after 100 double rubs with acetone.

It will be readily appreciated by those skilled in the art thatmodifications may be made to the invention without departing from theconcepts disclosed in the foregoing description. Such modifications areto be considered as included within the following claims unless theclaims, by their language, expressly state otherwise. Accordingly, theparticular embodiments described in detail herein are illustrative onlyand are not limiting to the scope of the invention which is to be giventhe full breadth of the appended claims and any and all equivalentsthereof.

1. A thermosetting composition comprising: (a) a fluoropolymercomposition comprising at least one reactive functional group containingfluoropolymer comprising; (i) units derived from a fluoromonomer havingthe formula F₂C═CXY, where X is CF₃ and Y is either F or CF₃, and (ii)units derived from at least one donor monomer, wherein the units (i) and(ii) are distributed along the fluoropolymer chain in a substantiallyalternating fashion; and (b) at least one crosslinking agent comprisingat least two functional groups reactive with the functional groups ofthe fluoropolymer.
 2. A substrate at least partially coated withthermosetting composition of claim
 1. 3. The thermosetting compositionof claim 1, wherein the fluoromonomer comprises hexafluoropropylene. 4.The thermosetting composition of claim 1, wherein the fluoromonomer ispresent in an amount of 25 to 50 mole percent, based on the total molesof material present in the fluoropolymer composition.
 5. Thethermosetting composition of claim 1, wherein the donor monomercomprises a mild donor monomer.
 6. The thermosetting composition ofclaim 1, wherein the donor monomer comprises a vinyl ester, anisobutylene type monomer, or a mixture thereof.
 7. The thermosettingcomposition of claim 8, wherein the vinyl ester comprises vinyl acetate,vinyl butyrate, vinyl 3,4-dimethoxybenzoate, vinyl propionate, vinylneodecanoate, vinyl pivolate, vinyl neononanoate, vinyl benzoate, or amixture thereof.
 8. The thermosetting composition of claim 1, wherein atleast 90 mol % of the units (i) and (ii) are distributed along thefluoropolymer chain in a substantially alternating fashion.
 9. Thethermosetting composition of claim 1, wherein the fluoropolymer has anumber average molecular weight ranging from 500 to 10,000 as determinedfrom gel permeation chromatography using polystyrene standards.
 10. Thethermosetting composition of claim 1, wherein the fluoropolymer has apolydispersity index of less than 2.0.
 11. The thermosetting compositionof claim 1, wherein the reactive functional groups of the fluoropolymercomprise hydroxyl groups.
 12. The thermosetting composition of claim 1,wherein the composition is a powder composition.
 13. The thermosettingcomposition of claim 1, wherein the composition is a liquid composition.14. The thermosetting composition of claim 13, wherein the component (a)is present in an amount of 40 to 80 weight percent based on the totalweight of the composition.
 15. The thermosetting composition of claim 1,wherein the component (b) is present in an amount of 20 to 40 weightpercent based on the total weight of the composition.
 16. Thethermosetting composition of claim 13, wherein the composition comprisesat least 40 percent solids based on the total weight of the composition.17. A method for coating a substrate comprising: (a) depositing on asubstrate the thermosetting composition of claim 1; (b) coalescing thethermosetting composition to form a substantially continuous film on thesubstrate; and (c) curing the thermosetting composition.
 18. Afluoropolymer composition comprising a fluoropolymer, wherein thefluoropolymer comprises: (a) units derived from a fluoromonomer havingthe formula F₂C═CXY, where X is CF₃ and Y is either F or CF₃, and (b)units derived from at least one donor monomer, wherein at least 90% ofthe units (a) and (b) are distributed along the fluoropolymer chain inan alternating fashion and wherein the fluoropolymer has a numberaverage molecular weight ranging from 500 to 10,000.
 19. A method ofmaking the fluoropolymer composition of claim 1, the method comprising:(a) providing a donor monomer composition comprising at least one donormonomer; (b) providing a fluoromonomer composition comprising at leastone fluoromonomer having the formula F₂C═CXY, where X is CF₃, and Y iseither F or CF₃; (c) providing at least one free radical polymerizationinitiator; (d) mixing the components provided in steps (a), (b), and(c); and (e) polymerizing the monomers at conditions that produce afluoropolymer wherein units derived from the fluoromonomer and unitsderived from the donor monomer are distributed along the fluoropolymerchain in a substantially alternating fashion.
 20. The method of claim19, wherein step (d) comprises separately and simultaneously adding andmixing the components provided in steps (a), (b), and (c).